Methods and systems for heart failure prevention and treatments using ultrasound and leadless implantable devices

ABSTRACT

The present invention relies on a controller-transmitter device to deliver ultrasound energy into cardiac tissue in order to directly improve cardiac function and/or to energize one or more implanted receiver-stimulator devices that transduce the ultrasound energy to electrical energy to perform excitatory and/or non-excitatory treatments for heart failure. The acoustic energy can be applied as a single burst or as multiple bursts.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 16/249,196, filed Jan. 16, 2019, now U.S. Pat. No. 11,376,439, whichis a continuation of U.S. patent application Ser. No. 15/138,582, fieldApr. 26, 2016, now U.S. Pat. No. 10,207,115, which is a divisional ofU.S. patent application Ser. No. 12/829,183, filed Jul. 1, 2010, nowU.S. Pat. No. 9,333,364, which is a divisional of U.S. patentapplication Ser. No. 11/468,002, filed Aug. 29, 2006, now U.S. Pat. No.7,765,001, which claims the benefit of U.S. Provisional PatentApplication No. 60/713,241, filed Aug. 31, 2005, the full disclosures ofwhich are incorporated herein by reference in their entireties.

The disclosure of this application is also related to U.S. patentapplication Ser. No. 11/315,023, filed on Dec. 21, 2005, now U.S. Pat.No. 7,610,092, which claims priority to U.S. Provisional PatentApplication No. 60/689,606, filed on Jun. 9, 2005, and to U.S. patentapplication Ser. No. 10/869,631, filed on Jun. 15, 2004, the fulldisclosures of which are incorporated herein by reference in theirentireties.

TECHNICAL FIELD

The methods and systems of this invention relate to the prevention andtreatment of heart failure by means of a leadless external orimplantable device.

Heart Failure (HF) currently affects over 5 million patients in theUnited States alone. This population has been steadily increasing due tooverall demographic aging and, in particular, the effects of newlife-prolonging treatments to patients with chronic cardiac conditions.HF is defined by the ACC/AHA Task Force as a complex clinical syndromethat impairs the ability of the ventricle to fill with or eject blood.HF generally results from one or more underlying factors includinghypertension, diabetes, valvular disease, cardiomyopathy, coronaryartery disease, or structural changes to the heart muscle. HF ischaracterized by reduced ventricular wall motion in systole and/ordiastole, and low ejection fraction. As the heart becomes less able topump a sufficient volume of blood to the system, patients developsymptoms of fluid retention, shortness of breath, and fatigue. Patientswith cardiac disease or patients who experience cardiac problems, e.g.,ischemic episodes, are highly likely to eventually develop HF. It willbe beneficial to offer preventative treatment to these patients so thatthey might avoid or postpone becoming HF patients.

BACKGROUND

New medications developed to treat HF have been generally ineffective,and device-based solutions appear to offer significant promise forafflicted patients in both preventing heart failure initially andameliorating the progression of heart failure. The following aredescriptions of four device-based therapies to treat, prevent, and/ordelay progression of HF.

First, there are several reports of using therapeutic ultrasound toincrease cardiac contractility, reduce aortic pressure, cause coronaryvasodilatation, or increase tissue perfusion (tissue sonication). Thesereports describe the application of continuous and pulsed ultrasoundover a wide range of treatment durations, timing intervals, ultrasoundfrequencies, and ultrasound intensities. In isolated rat papillarymuscle, Forester et al. demonstrated increased contractility withcontinuous wave ultrasound. They speculated that the increase incontractility was due to the thermal effects or mechanical tensioneffects of ultrasound energy on the sarcolemma (external musclemembrane). Dalecki et al. found that the delivery of pulsed ultrasoundto the frog heart in systole resulted in a reduction in the peak aorticpressure. Miyamoto et al. reported vasodilation of coronary arteries incanine studies by short term ultrasound therapy, with the magnitude ofthe dilation similar to that of intracoronary nitroglycerin. Theyspeculated that the observed coronary vasodilation was a direct effecton vasomotor tone, and reported no temperature change to implicate athermal effect. Suchkova et al., applied ultrasound to the surface ofrabbit limb muscles following arterial ligation, and found that tissueperfusion was increased, accompanied by histologic evidence of dilatedcapillary beds. They further found this improvement in perfusion to beblocked by inhibition of nitric oxide synthase, implying that themechanism of effect was dependent upon nitric oxide. Finally, animalstudies have shown that ultrasound treatment can cause new myocardialtissue growth in conditions of chronic ischemia, and this is thought tobe due to up-regulation of growth factor expression.

Thus, a number of underlying mechanisms have been proposed to explainwhy therapeutic ultrasound may have beneficial effects on cardiacfunction. It is possible that increased myocardial contractility,reduced aortic pressure, coronary vasodilation, and increased tissueperfusion occur by separate or related mechanisms. For example, thevasodilation may be secondary to the increased myocardial demand causedby increased contractility. Alternatively, a reduction in aorticpressure (afterload) may result in increased contractility. Increasedtissue perfusion may be a manifestation of vasodilation at the capillarylevel.

While the exact mechanism(s) and sequence of events are not wellunderstood, the beneficial effects of therapeutic ultrasound on cardiacfunction can be utilized to improve the care of patients with heartfailure both chronically and during acute exacerbations. Long termimprovement in heart failure treatment is possible with chronicintermittent ultrasound administration. Coronary artery disease is theunderlying cause of HF in two-thirds of HF patients and coronary arterydisease can lead to acute ischemic episodes, which can be treated byimproving blood flow (reperfusion). Since ultrasound therapy can improveblood flow, therapeutic ultrasound can, thus, prevent HF. We havedescribed the use of ultrasound in co-pending application Ser. No.10/869,631 (Attorney Docket No. 021834-000310), with methods and systemsfor leadless implantable devices that directly prevent and/or treatheart failure using ultrasound energy.

Second, the indications for permanent cardiac pacemaker implantationhave greatly expanded to include the treatment of heart failure bypacing both the left and right ventricle, called cardiacresynchronization therapy (CRT) or bi-ventricular pacing. Randomizedclinical trials have shown significant morbidity and mortality benefitswith bi-ventricular pacing, especially when combined with an implantablecardioverter defibrillator (ICD). As described in co-pending applicationSer. No. 11/315,023 (Attorney Docket No. 021834-000820US), and Ser. No.11/315,524 (Attorney Docket No. 021834-001010US), a method of cardiacstimulation uses one or more implantable acoustic receiver-stimulatorsfor cardiac stimulation, along with an implanted or externally-appliedultrasound controller-transmitter. Using this leadless system to avoidlead limitations and complications and gain other potential advantagesas described in the co-pending applications, CRT therapy is applied tooptimal single or multiple sites in the left or right heart and mostnotably endocardial left ventricular sites.

Third, another device therapy applying electrical current to the heartmuscle is called Cardiac Contractility Modulation (CCM). These systemshave some similarities to conventional cardiac pacemakers, in that theycomprise a pulse generator implanted in the pectoral region of the chestand transvenous leads having electrodes in direct contact with hearttissue; in some cases, conventional pacemaker leads have been used inCCM therapy. However, in a conventional cardiac pacemaker, electricalcurrent is delivered at sufficient amplitude and duration at a time inthe cardiac cycle that will initiate a heart beat, known in the art asexcitation. In contrast, for CCM therapy, electrical current isdelivered during or immediately after a heart beat when the heart isunable to initiate another beat, known in the art as the absoluterefractory period of the heart. The amplitude and duration of theelectrical current would be sufficient for excitation, but since it isdelivered in this refractory period it is thus considerednon-excitatory. Instead of initiating a heart beat via excitation, theelectrical field or electrical current delivered for CCM increasestissue contractility during the heart beat. As noted earlier, increasedtissue contractility leads to improved cardiac function. It has beenshown in basic investigational studies using this CCM approach that theaction potential duration is prolonged during this non-excitatoryelectrical field delivery. It is thought that the underlying mechanismis an increase in calcium transport into the cells.

Early animal studies (Mohri et al.) employed two pairs of electrodes,one pair in the anterior LV wall and one pair in the posterior wall;each with approximately 3 cm inter-electrode distance. CCMnon-excitatory electrical field delivery (20 mA biphasic square-waves of30 ms duration) was delivered 30 ms after local R wave detection,between each electrode pair. An increase in contractility was found witheither anterior or posterior delivery, but was greatest withsimultaneous delivery to both the anterior and posterior pairs. Theincrease in contractility only occurred in the regions of electricalcurrent delivery.

In acute human studies (Pappone et al.), CCM therapy was deliveredeither across two selected poles of an octapolar catheter in thecoronary sinus (CS), on the epicardial aspect of the LV or on the RVseptum from the tip electrode to the ring electrode of a commerciallyavailable active fixation pacing lead. The CCM current used was abiphasic, square-wave pulse 20-40 ms in duration, delivered 30-60 msafter detection of an electrical pulse using the local electrogram, withpulse amplitudes up to 14 mA. With LV delivery of 10 mA to the CS, somepatients complained of chest discomfort. With RV septum delivery, 14 mAwas able to be delivered without chest discomfort. Acute improvement inLV function was similar with LV or RV delivery; approximately a 9%increase in pressure gradient dP/dt_(max) and 10% increase in aorticpulse pressure.

One example of a CCM device is an Optimizer™ II (Impulse Dynamics,Israel). These have been implanted in patients and have been shown toimprove cardiac function (Pappone et al., Stix et al.). This deviceemploys one commercially available right atrial lead used for sensingonly, and 2 commercially available transvenous bipolar active fixationleads implanted in the RV septum used for sensing a local electrogramand delivery of non-excitatory electrical current.

Because CCM devices use leads similar to cardiac pacemakers, they aresubject to all the limitations and complications associated withcurrently available cardiac pacemakers. These lead issues have beenextensively identified in our co-pending applications listed above.Additionally, although animal studies had shown greater efficacy withplacement of the electrodes on the left ventricle, in clinical studiesusing coronary sinus leads for left ventricular non-excitatory CCMtherapy, patients experienced chest pain, attributed to stimulation ofthe phrenic nerve. In the same patients, endocardial delivery to theright ventricular septum did not cause discomfort. It is likely, basedon animal study results, that CCM therapy would be substantiallyimproved using a system that enables endocardial left ventricularnon-excitatory therapy.

Therefore, it would be desirable to provide a system without the needfor transvenous leads, with the ability to optimally select sites on theendocardium, particularly in the left ventricle, and to select multiplesites for CCM delivery of non-excitatory electrical current.

Fourth, the concept of selective site pacing to initiate a preferredpattern of cardiac activation and/or mechanical contraction has beenrecently put forth to prevent heart failure in patients needingpermanent pacing for bradycardia indications. Traditionally, thestandard ventricular site for stimulation has been the RV apex forreasons of lead stability and ease of implantation. However, recentrandomized clinical trials of patients requiring bradycardia pacing(DAVID and PAVE) have led to the conclusion that the RV apex location isdeleterious. The concept of selective site pacing has emerged, and hasled to the reevaluation of all traditional pacing sites. New stimulationsites being evaluated require the use of non-passive fixation tips andmore precise implant techniques. The ideal site(s) may be within theleft ventricle in areas inaccessible using transvenous leads from withinthe coronary sinus. Selective site left ventricular or right ventricularstimulation alone may provide improved heart functioning or preventionof heart failure without the need for bi-ventricular stimulation. Itwould be desirable to provide selective site pacing with previouslyreferred to leadless methods and systems using one or more implantableacoustic receiver-stimulators for cardiac stimulation, along with animplanted or externally-applied ultrasound controller-transmitter. Thereceiver-stimulator would be implanted in the left and/or rightventricle at one or more locations that initiate a preferred pattern ofcardiac activation and/or mechanical contraction.

It would be desirable to treat patients who have had cardiac problems toprevent or delay them from becoming HF patients. It would be ideal toprovide a single system to take advantage of the benefits ofsonification, pacing and CCM and either based on user preference,pre-programmed therapy, or physiologic parameters that are measured,individual or combination treatments (sonication, pacing or CCM) couldbe provided.

Thus, it would further be desirable to provide an implantable devicethat combines the beneficial effects of direct application of ultrasoundenergy to cardiac tissue with the beneficial effects of a leadlesselectrical delivery device for cardiac resynchronization stimulationtherapy, cardiac contractility modulation therapy, and/or selective sitepacing therapy in order to improve cardiac function in heart failurepatients or to prevent heart failure in other patients.

2. Description of the Background Art

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SUMMARY

The devices of the present invention deliver ultrasound energy to theheart and/or deliver ultrasound energy to receiver-stimulator devices.Delivered at therapeutic levels, the ultrasound energy directly improvescardiac function by increasing contractility, vasodilation, and tissueperfusion, etc. This leads to prevention of HF in patients who arelikely to become HF patients, if left untreated, and in patients who arealready diagnosed with HF. Delivered at sufficient amplitudes, theultrasound energy is transduced into electrical energy by implantedreceiver-stimulator devices that have been implanted in the hearttissue, providing either excitatory or non-excitatory energy deliveryfor the treatment of heart failure. In combination, ultrasound therapyand receiver-stimulator device therapy provide multiple benefits asheart failure therapies, including preventing patients from degeneratinginto HF. The use of ultrasound as the single energy source providesefficient selection of individual and combined therapies, as well astissues sites, for delivering the therapy.

The present invention relies on acoustic energy delivery using anexternal or implantable device to provide beneficial effects forpatients with heart failure including 1) the ability to improve cardiacfunction from the exposure of acoustic energy to cardiac tissue, and/or2) the ability to transmit acoustic energy to implanted receivers toprovide excitatory and non-excitatory stimulation, in patients sufferingfrom or at risk of heart failure.

We have previously disclosed methods and systems to treat heart failureby means of a leadless implantable device delivering vibrational(ultrasound, acoustic) energy from a controller-transmitter device todirectly improve cardiac function. We have also previously disclosedmethods and devices of leadless implantable systems for the electricalstimulation of cardiac tissue using ultrasound as a means to transmitenergy and signal information from a controller-transmitter devicethroughout the body to one or more receiver-stimulator devicescontaining means to receive such ultrasound, convert it into electricalenergy, and then apply that electrical energy to stimulating electrodesas cardiac resynchronization therapy for the treatment of heart failure.See U.S. patent application Ser. No. 11/315,023, now U.S. Pat. No.7,610,092, filed Dec. 21, 2005; U.S. patent application Ser. No.11/315,524, now U.S. Pat. No. 7,606,621, filed Dec. 21, 2005; and U.S.patent application Ser. No. 10/869,631, filed Jun. 15, 2004, the fulldisclosures of which are incorporated herein by reference in theirentireties.

In all these co-pending applications, acoustic energy is applied from anexternal or implanted controller-transmitter to the heart tissue toprovide at least one of an increase in contractility, vasodilation,tissue perfusion, and/or an increase in cardiac output for the treatmentof heart failure.

In some of these co-pending applications, acoustic energy is appliedfrom an external or implanted controller-transmitter to implantedreceiver-stimulator devices in the heart to provide electrical deliveryfor bi-ventricular pacing or selective site pacing.

It is an intent of this invention to provide methods and systems for theleadless electrical delivery of non-excitatory therapy in cardiaccontractility modulation for the treatment of heart failure. It is afurther intent of this invention to provide methods and systems for theleadless electrical delivery of excitatory therapy for the prevention ofheart failure. It is still a further intent of this invention to providemethods and systems to select and deliver separate heart failuretreatment and preventive therapies within a single system. It is yetanother intent of this invention to provide methods and systems tocombine and deliver in a single system multiple heart failure treatmentand preventive therapies to yield multiple therapeutic benefits.

External or implanted controller-transmitters according to the presentinvention are configured to apply acoustic energy to at least a portionof the heart, usually including at least a ventricular region(s) of theheart and typically including regions of the heart with implantedreceiver-stimulator devices.

A controller-transmitter device may be implanted utilizing knownsurgical techniques subcutaneously, above or beneath the pectoralmuscles, near the heart. This device will typically contain some, most,or all elements of currently available pacemaker systems, with specificadaptations pertinent to this invention. Such typical elements mayinclude a power source, such as a battery or a rechargeable battery;logic control and timing circuitry; a sensing system, typicallycomprising sensing electrodes, motion detectors, and other types ofphysiologic sensors; signal conditioning and analysis functions for thevarious electrodes and detectors; and a system to communicate with anoutside console for data transmission, diagnostic, and programmingfunctions typically through a radiofrequency (RF) link. Additionally,the controller-transmitter device usually contains an ultrasoundamplifier and an ultrasound transducer to generate acoustic energy, andto transmit such energy in the general direction of the heart andspecifically in the direction of the implanted receiver-stimulatordevice. Beam profiles of the transmitted acoustic energy may be adaptedto target portions of the heart or implanted receiver-stimulatordevices. The duration, timing, and power of the acoustic energytransmission would be controlled as required, in response to detectednatural or induced physiological events or conditions, and perprogrammed parameters of the device, by the logic control electronics.

In order to provide excitatory or non-excitatory electrical delivery tocardiac tissue employing ultrasonic energy transfer, the presentinvention comprises an implantable receiver-stimulator device adapted tobe implanted at or attached to the desired location eitherendocardially, epicardially, or intramyocardially. Various techniquesand tools (catheters, stylets) that are commonly known could be used toimplant the receiver-stimulator device at these locations. Thereceiver-stimulator would be adapted to provide permanent attachment atthe implant site including possibly helical coils, barbs, tines, clips,or the like, or by bonding onto its outer surface materials which areknown to stimulate cellular growth and adhesion. Alternatively, thereceiver-stimulator could be adapted for implantation in the coronaryvasculature at preferred sites for stimulation, e.g., being incorporatedinto a stent-like platform suitable for intravascular delivery anddeployment. Functionally, the receiver-stimulator device comprises 1) anultrasound transducer to receive the acoustic energy transmitted from acontroller-transmitter device and transform it into electrical energy,2) an electrical circuit to transform the alternating electrical energyinto a direct current or a waveform having other characteristics (e.g.,multiphase waveforms), and 3) electrodes to transfer the electricalenergy to the myocardium.

A single receiver-stimulator device may be implanted as described abovefor single site excitatory or non-excitatory electrical delivery tocardiac tissue. Alternatively, a plurality of receiver-stimulatordevices could be implanted to deliver excitatory or non-excitatoryelectrical energy to cardiac tissue, either by simultaneous, sequentialor independent activation of the receiver-stimulator devices. Thetransmitted acoustic energy can activate the stimulators simultaneouslyor sequentially through fixed or programmable delays after receiving thesame transmitted acoustic energy, or independently by responding only toacoustic energy of a specific character (i.e., of a certain frequency,amplitude, or by other modulation or encoding of the acoustic waveform)intended to energize only that specific device.

In one embodiment, a controller-transmitter would contain programmableparameter settings to activate receiver-stimulators that have beenimplanted at critical sites to deliver leadless non-excitatory CCMtherapy to improve cardiac function of heart failure patients. Aplurality of receiver-transmitters would be implanted into the leftand/or right heart at selected locations in order to provide anon-excitatory electrical field. The controller-transmitter wouldinclude sensing electrodes on, connected to, or incorporated into itsexternal surface and signal processing circuitry and algorithms to allowit to detect the patient's electrogram (electrocardiographic recording).Signal processing and specialized algorithms would recognize intrinsicatrial and/or ventricular activation and possibly alsoelectrocardiographic indices of action potential duration such as the QTinterval. Following a detected intrinsic ventricular activation and aprogrammed delay interval, the controller-transmitter would thenactivate the receiver-stimulator devices at energy levels that aretherapeutic.

In another embodiment, a controller-transmitter would containprogrammable parameters to activate receiver-stimulators that have beenimplanted at critical sites to deliver excitatory (pacing) therapy toprevent heart failure.

In yet another embodiment, a controller-transmitter would containprogrammable parameter settings to provide direct therapeutic sonicationof ventricular tissue, and contain programmable parameters to activatereceiver-stimulators to deliver leadless bi-ventricular pacing therapyor site selected pacing therapy for heart failure, and containprogrammable parameters to activate receiver-stimulators that have beenimplanted at critical sites to deliver pacing therapy as a prevention ofheart failure, and contain programmable parameters to activatereceiver-stimulators that have been adapted and implanted in criticalsites to deliver CCM therapy to improve the tissue condition of heartfailure patients.

In another preferred embodiment, a controller-transmitter would containprogrammable parameters settings to deliver combinations of therapy fordirect therapeutic sonication of ventricular tissue, leadlessbi-ventricular or critical site pacing, heart failure prevention pacing,and/or CCM therapy. In such an embodiment one or morereceiver-stimulator elements adapted for its specific function wouldnecessarily be implanted at desired locations within the heart,preferably fully embedded within the myocardium. The specializedcontroller-transmitter would then be implanted subcutaneously at alocation allowing sonication of tissue in both ventricles and activationof one or more implanted receiver-stimulators. Any of the therapiesdescribed could be used independently or in combination to accomplishmulti-beneficial therapy. The controller-transmitter would includesensing electrodes on or incorporated into its external surface andsignal processing circuitry and algorithms to allow it to detectphysiologic parameters (e.g., electrograms, pacing artifact signals froman implanted conventional pacemaker, pressure, heart sounds,motion/activity, etc.) to allow algorithmic adjustment to one or moretherapies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the components of a system constructedaccording to the principles of the present invention.

FIG. 2 illustrates a controller-transmitter implanted over a patient'sheart and in communication with a receiver-stimulator and an externalprogrammer.

FIG. 3a illustrates prior art timing parameters.

FIG. 3b illustrates a system for performing CCM therapy directly oncardiac tissue.

FIGS. 4a-4d illustrate different implantation sites for thereceiver-stimulator.

DETAILED DESCRIPTION

The present invention relies on a controller-transmitter device todeliver ultrasound energy to cardiac tissue to directly improve cardiacfunction and/or to energize one or more implanted receiver-stimulatordevices that transduce the ultrasound energy to electrical energy toperform excitatory and/or non-excitatory treatments for heart failure.The acoustic energy can be applied as a single burst or as multiplebursts with appropriate selection of the following parameters:

Parameter Value Range Ultrasound frequency 20 kHz-5 MHz Ultrasound BurstDuration  0.1 [LS-100 mS Duty Cycle 0.001-6.0% Mechanical Index <1.9

FIG. 1 is a block diagram of the present invention. An implantablecontroller-transmitter device 1 contains an ultrasound transducer 16 (ormultiple transducers) of appropriate size(s) and aperture(s) to generatesufficient acoustic power to achieve the desired heart failure therapy.The transducer(s) 16 within the controller-transmitter device 1 areconstructed of specific designs, including aperture size, acousticfrequency, materials, and arrangement to provide the appropriate beamcharacteristics for individual embodiments, implant sites, and patientcharacteristics. The controller-transmitter 1 contains the power source,typically a battery 10, ultrasound amplifier 15, transmission powerconditioning 17, control and timing electronics and logic 14,physiologic sensor interface electronics 12, sensors 11 eitherencapsulated in the device or connected to the device, and acommunication module 13 typically an RF communication interface to anexternal control and programming device 3. An externalcontroller-transmitter would contain the same elements, except theexternal programmer 3 and RF communication module 13. The externalcontroller-transmitter would have an operator-controlled interface (notshown) to adjust device parameters.

The transducer(s) 16 may comprise a single element or several elementsin a linear, two-dimensional, or segmented array (not shown). In thecase of an array, each element may have its own amplifier 15 and controland timing electronics and logic 14 such that the acoustic beam might befocused or diffused depending on the desired function or effect, orsteered to a desired location, or that the beam may be swept to coverseveral sites in sequential order, or any combination thereof.

The one or more receiver-stimulator implants 2 contain a receivertransducer 18, circuitry 19 to detect, impedance match, and convert thereceived ultrasound energy into an electrical output, and electrodes 20.Multiple receiver-stimulator devices 2 may function simultaneously; itis also possible for multiple devices to function sequentially byincorporating different delays within the circuitry 19, orindependently, either by responding only to a specific transmittedfrequency by steering the transmit beam to specific devices, or throughthe use of a selective modulation technique such as amplitudemodulation, frequency modulation, pulse width modulation, or throughencoding techniques including time-division multiplexing, which would bediscriminated by adapting circuitry 19.

FIG. 2 illustrates the functional components of the present inventionfor an implanted embodiment. The controller-transmitter device 1containing the transmitting transducer would be implanted typically justbeneath the skin in the subcutaneous space but could also be placedbeneath the pectoral muscles. In particular, it is desirable to be ableto direct the ultrasonic energy over the left ventricle in order toassure maximum effectiveness. As the heart is located beneath the ribsand sternum, the controller-transmitter device 1 must be properlylocated to deliver the energy. At frequencies lower than 1 MHz, acousticattenuation due to bone and cartilage is less problematic.

The receiver-stimulator device(s) 2 would be implanted typically usingan endocardial placement technique by an active fixation mechanism suchas a helical screw-in element. Alternatively the receiver-stimulatordevice(s) 2 could be implanted using a minimally invasive surgicalapproach to the epicardial aspects of the heart or deliveredtransvascularly into, for example, the coronary sinus. Locations for thereceiver-stimulator devices would be chosen to optimize the desiredelectrical therapy.

The controller-transmitter device 1 would typically includephysiological sensors 11 (not shown) such as electrodes disposed on theouter surface of the device, for detecting the patient's electrogram,and in certain embodiments additional physiological sensors includingbut not limited to sensors which would detect the patient's motion,blood pressure, respiration, and/or heart sounds. Circuitry andalgorithm logic 14 for utilizing these signals for control of thedevices' therapeutic function could be incorporated in the system. Suchelectrodes and other sensors would be preferably disposed on orincorporated into or within the housing of the controller-transmitterdevice.

An external programmer 3 is used to program device parameters in thecontroller-transmitter 1, typically using an RF telemetry link.Programming of the controller-transmitter includes the selection of oneor more of the following types of therapies: (i) Sonication of hearttissue to improve cardiac function; (ii) Site-selected pacing forprevention of heart failure; (iii) Multi-site pacing (e.g.,bi-ventricular pacing) for treatment of heart failure; and (iv) CardiacContractility Modulation to improve contractility.

Alternatively, the acoustic transmitter function for direct therapeuticsonication of heart tissue might also be incorporated within a devicedelivering conventional lead-based electrical current (not shown), forexample, within a CRT device or within a CCM device wherein theconventional lead/electrode system would provide sensing from andelectrical delivery to cardiac tissue and the acoustic transmissionwould provide ultrasound therapy for heart failure.

FIG. 3a , shown adapted from prior art (Mohri), is an example toillustrate the types of timing needed within for the control circuitry14 to perform CCM therapy using the present invention. Sensingelectrodes on a controller-transmitter device 1 provide a signal similarto the surface ECG shown in the diagram. The onset of electricalventricular activation is detected, and after a specified delay (hereshown as 30 msec), the transmitter delivers acoustic energy for aspecified duration which is transduced by circuitry 19 into anappropriate electrical waveform. The duration of the electrical delivery(here shown as 30 msec) is equal to the duration of acoustic delivery.In this example, the electrical waveform is biphasic (positive squarewave followed by negative square wave) with an amplitude of 20 mA, butother waveforms may be used.

FIG. 3b shows a preferred embodiment for a system combining directacoustic therapy to the cardiac tissue with CCM therapy. In FIG. 3b ,two receiver-stimulator devices 2 are implanted into the rightventricle, one in the septum and the other at the apex. Other implantlocations in the right and left ventricle may be selected for any numberof receiver-stimulators 2. Inherent ventricular activation is detectedfrom sensing electrodes incorporated on the controller-transmitter 1whereby the control circuitry properly times the initiation of thedelivery of acoustic energy to the two implanted receiver-stimulators 2to initiate non-excitatory therapy.

FIGS. 4a-4d depict various illustrations of receiver-stimulator implantsite selections. FIG. 4a is a cross-sectional view of the heart showinga single receiver-stimulator device 2 implanted into the leftventricular myocardium. Such an embodiment may be functional for sitespecific pacing for the prevention of heart failure in a patient needingbradycardia pacing support, for site specific pacing for the treatmentof heart failure, or for CCM therapy to improve cardiac contractility ina heart failure patient. As shown, with appropriate placement of thecontroller-transmitter 1, both the cardiac tissue and thereceiver-stimulator 2 will receive ultrasound waves thus providing anopportunity for sonication therapy in a heart failure patient.

FIG. 4b is a cross-sectional view of the heart showing a singlereceiver-stimulator 2 implanted into the ventricular septum, receivingacoustic energy from controller-transmitter 1. Similarly, such anembodiment may be functional for site specific pacing for the preventionof heart failure in a patient needing bradycardia pacing support or forCCM therapy delivery to improve the wall motion characteristics of theseptum in a patient with HF.

FIG. 4c shows a further adaptation wherein two receiver-stimulatordevices 2 are implanted to achieve a completely leadless multi-sitepacemaker configuration for example as in bi-ventricular pacing or amulti-site CCM therapy delivery for HF treatment. The firstreceiver-stimulator 2 is shown attached to the right ventricular apexwith the second being attached to the left ventricular free wall. Bothreceiver-stimulator devices 2 and the ventricles receive acoustic energyfrom controller-transmitter 1 simultaneously. Direct beneficialsonication therapy may be delivered to the ventricles. Excitatory(pacing) and non-excitatory (CCM) therapy may be delivered eithersimultaneously or selectively.

FIG. 4d shows another alternative embodiment. In this example, fourreceiver-stimulator devices 2 are implanted into the right and leftventricle and can be used for multiple therapy concepts. As in FIG. 4c ,since the ultrasound is delivered to the cardiac tissue andreceiver-stimulators simultaneously, direct beneficial sonicationtherapy may be delivered simultaneously. Excitatory (pacing) andnon-excitatory (CCM) therapy may be delivered either simultaneously orselectively.

Optionally, but not shown, a receiver-stimulator 2 could also beimplanted into the atrial tissues of the heart. Optionally, but notshown, this multi-therapy concept could integrate the ultrasoundsonication therapy with a conventional dual chamber pacemaker (DDD),dual chamber ICD, bi-ventricular pacemaker (CRT-P), biventricularpacemaker ICD (CRT-D), or a CCM therapy device.

Optionally, the invention can provide three types of heart failuretreatments to the patient either separately or in combination; directsonication of the ventricular tissue, cardiac contractility modulationtherapy, and excitatory pacing stimulation.

I/We claim:
 1. A system for the delivery of therapy to a heart of apatient, comprising: a sensor configured to sense a physiologicparameter of the patient; an acoustic transmitter configured to transmitacoustic energy into a body of the patient; and control circuitryoperably coupled to the sensor and the acoustic transmitter, wherein—the control circuitry is configured to control the acoustic transmitter,based at least in part on the physiologic parameter sensed via thesensor, to adjust a therapy for improving cardiac function and/orpreventing deterioration of cardiac function of the heart of thepatient, and the control circuitry is configured to control the acoustictransmitter to adjust the therapy by (a) transmitting the acousticenergy to a remote receiver-stimulator implanted at the heart of thepatient and/or (b) transmitting the acoustic energy to provide directsonication to the heart of the patient.
 2. The system of claim 1 whereinthe therapy is selected from the group consisting of (a) ultrasoundsonication of heart tissue to improve cardiac function, (b) ultrasoundsonication of heart tissue to prevent deterioration of cardiac function,(c) leadless pacing to improve cardiac function, (d) leadless pacing toprevent deterioration of cardiac function, (e) leadless cardiaccontractility modulation to improve cardiac function, and (f) leadlesscardiac contractility modulation to prevent deterioration of cardiacfunction.
 3. The system of claim 1 wherein the cardiac function is oneor more of contractility, vasodilation, tissue perfusion, and aorticpressure.
 4. The system of claim 1 wherein the control circuitry isconfigured to control a duration of transmission of the acoustic energy,a timing of transmission of the acoustic energy, and/or a power oftransmission of the acoustic energy.
 5. The system of claim 1, furthercomprising a housing, wherein the control circuitry and the acoustictransmitter are positioned within the housing, and wherein the sensor ispositioned on an outer surface of the housing.
 6. The system of claim 1wherein the physiological parameter is selected from the groupconsisting of an electrogram, a pacing artifact signal detected from apacemaker implanted within the patient, a pressure, a heart sound, amotion of the heart of the patient, and an activity of the heart of thepatient.
 7. The system of claim 1, further comprising thereceiver-stimulator, wherein the receiver-stimulator is configured todirectly contact cardiac tissue of the patient and to stimulate thecardiac tissue.
 8. The system of claim 7 wherein the therapy is leadlesspacing to treat heart failure.
 9. The system of claim 1 wherein thephysiologic parameter is an electrogram.
 10. The system of claim 1wherein the physiologic parameter is blood pressure.
 11. The system ofclaim 1 wherein the acoustic transmitter is implantable in the body ofthe patient.
 12. A method of delivering therapy to a heart of a patient,the method comprising: sensing a physiologic parameter of the patientwith a sensor implanted in the patient; communicating the physiologicparameter from the sensor to control circuitry; and based on the sensedphysiologic parameter, adjusting, via the control circuitry, a therapyfor improving cardiac function and/or preventing deterioration ofcardiac function of the heart of the patient by— transmitting acousticenergy to a remote receiver-stimulator implanted at the heart of thepatient, and/or transmitting the acoustic energy to provide directsonication to the heart of the patient.
 13. The method of claim 12wherein the therapy is selected from the group consisting of (a)ultrasound sonication of heart tissue to improve cardiac function, (b)ultrasound sonication of heart tissue to prevent deterioration ofcardiac function, (c) leadless pacing to improve cardiac function, (d)leadless pacing to prevent deterioration of cardiac function, (e)leadless cardiac contractility modulation to improve cardiac function,and (f) leadless cardiac contractility modulation to preventdeterioration of cardiac function.
 14. The method of claim 12 whereinthe cardiac function is one or more of contractility, vasodilation,tissue perfusion, and aortic pressure.
 15. The method of claim 12wherein adjusting the therapy comprises adjusting a duration oftransmission of the acoustic energy, a timing of transmission of theacoustic energy, and/or a power of transmission of the acoustic energy.16. The method of claim 12 wherein transmitting the acoustic energycomprises controlling an acoustic transmitter positioned to transmitacoustic energy into a body of the patient.
 17. The method of claim 16wherein the acoustic transmitter is implantable in the body of thepatient.
 18. The method of claim 12 wherein sensing the physiologicparameter wherein the sensor is carried by the receiver-stimulator. 19.The method of claim 12 wherein the therapy is leadless pacing to treatheart failure.
 20. The method of claim 12 wherein the physiologicparameter is an electrogram.